This invention relates to electromagnetic projectile launching systems and more particularly to such systems where a plasma (arc) is used to accelerate the projectile.
Electromagnetic projectile launchers are known which comprise a pair of conductive rails, a sliding conductive armature between the rails, a source of high current, and a switch for commutating this current into the rails and through the armature. This places an electromagnetic force on the armature which propels it along the conductive rails. Launchers which utilize metallic armatures have experienced considerable rail damage caused by the sliding armature, particularly where high armature velocities are involved. In these cases, a plasma (arc) armature may be more suitable.
The principal disadvantage to the use of a plasma propelling armature has been the damage that occurs to the breech section of the launcher rails during formation of the plasma. Once the plasma is moving, very little, if any, damage occurs to the rails. Copending application entitled "Electromagnetic Launcher With Self Augmented Rails," Ser. No. 137,059, filed Apr. 3, 1980 by Demeny and Litz, assigned to the present assignee, and now U.S. Pat. No. 4,347,463, discloses a means for establishing an arc for propelling a projectile comprising a shoolting wire or fuse which initiates current flow between the rails, disintegrates, and thereby forms an ionized plasma or arc through which current continues to flow.
The present invention utilizes a switching rail system similar to that disclosed in a copending application entitled "A Swithcing System For High DC Current," Ser. No. 100,302, filed Dec. 4, 1979 by Kemeny, assigned to the present assignee and now abandoned. In a switching rail system, an arc is inherently formed during the commutation of current from the switching rails to the projectile launching rails. The arc is sustained in the present invention and used as the projectile propelling armature. This results in the use of a plasma driving armature which minimizes damage to the rails in the breech area, thereby allowing multi-shot firing without the necessity for system maintenance.
A pair of switching rails is connected through a switch to a source of high DC current. A sliding conductive switch armature is located between the switching rails. When the switch is closed, current flows through the switching rails and switch armature, thereby electromagnetically propelling the switch armature along the rails. As the switch armature passes the ends of the conductive portion of the switching rails, it breaks the circuit, causing an arc to form between the switching rails and the switch armature. An aperture is provided in one of the switching rails near arc location, providing an opening leading to the breech section of a pair of projectile rails. Electromagnetic forces cause the arc to pass through the aperture and into the breech section of the projectile rails, where it serves as the projectile driving armature.